Longtime Preposterous readers know that there's nothing that excites me quite like dark energy. It is, after all, about seventy percent of the energy of the universe, so there's a lot to be excited about. Not to mention that we understand very little about it, and it might provide crucial clues to the ultimate reconciliation of gravity and quantum mechanics, so it's worth paying attention to.

(click for larger version -- credit Sky & Telescope)

Still, dark energy (a nearly-uniform energy density in every cubic centimeter of space, practically constant through time) is a tricky concept, so it's worth taking every opportunity we have to explain what we know about it and what we're still trying to learn. I have an article in the March issue of Sky & Telescope that attempts to survey just that. (Not available online, I'm afraid.) The article, unimaginatively titled "Dark Energy and the Preposterous Universe," is basically a written version of the talk that I often give to popular audiences. Some day I will get around to writing an entire book that fleshes out these ideas even more. In my spare time.

If you'd like to actually hear a popular talk on dark energy live and in person, book your tickets now to Aspen, where I'll be giving a public lecture on February 16th, in association with the winter conference on particle physics. Nobody ever said that physicists didn't know how to live. Even more exclusively, I'm organizing a dark energy symposium at the upcoming meeting of the American Association for the Advancement of Science in Washington DC. It's a great line-up of speakers: Adam Riess talking about supernova measurements of the expansion of the universe, Licia Verde talking about how we can use the CMB and large-scale structure to constrain dark energy, John Carlstrom on building new telescopes to observe the Sunyaev-Zeldovich effect in clusters of galaxies as a novel handle on the evolution of the universe, Lenny Susskind on the string theory landscape and the anthropic principle, and Gia Dvali on brane worlds and modified gravity. Of course, you have to register for the meeting, so it's not easy to actually go to the symposium. But there should be a good selection of journalists in attendance, so hopefully the message will be spread far and wide.